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The Washington Post's new report detailing the NSA's collection of location information on cell phones is blunt. The NSA's ability to track location is "staggering," meaning that it is "able to render most efforts at communications security effectively futile." Including the efforts of Edward Snowden.

According to documents provided by Snowden, the agency collects 5 billion location records around the world a day, a number that a May 2012 NSA memo suggested could be "outpacing [its] ability to ingest, process and store" the information. In part, this data is collected by tapping underseas cables that shuttle information within cellular telephone company networks.

The information it collects is extremely revelatory, tracking when phones are turned on and off and move into the range of different cell towers. (The Post has a great infographic showing how cell towers can be used for locating targets, part of which is below.) The description of how the analysis of this data works is remarkable.

Like encryption and anonymity tools online, which are used by dissidents, journalists and terrorists alike, security-minded behavior — using disposable cellphones and switching them on only long enough to make brief calls — marks a user for special scrutiny. [Analysis program] CO-TRAVELER takes note, for example, when a new telephone connects to a cell tower soon after another nearby device is used for the last time.

Side-by-side security efforts — when nearby devices power off and on together over time — “assist in determining whether co-travelers are associated … through behaviorally relevant relationships,” according to the 24-page white paper, which was developed by the NSA in partnership with the National Geospatial Agency, the Australian Signals Directorate and private contractors.

It's not new information that the agency collects some location information. Shortly after 9/11, the agency used a phone's location to help the CIA target a (successful) drone strike. The NSA doesn't capture location information on Americans, it claims, having curtailed an experiment in doing so several years ago. (Whether or not tracking Americans' location information violates the Constitution is still a subject of debate.) But "incidental" collection, gathering information on Americans unintentionally clearly happens even overseas. The Post asked about how often that happens.

“It’s awkward for us to try to provide any specific numbers,” one intelligence official said in a telephone interview. An NSA spokeswoman who took part in the call cut in to say the agency has no way to calculate such a figure.

What's particularly remarkable about the new revelation is how the NSA uses location information to build out its social network information. As noted above, it can tell from the behavior and movement of phones if two people are in the same place together or not. Even without GPS information, the NSA can guess based on cell tower connections when people are together — information that the cell companies themselves maintain.

When Snowden met with journalists Glenn Greenwald and Laura Poitras for the first time in Hong Kong, he had them put their phones in the fridge to block them from connecting to any nearby cell towers. According to the documents he handed over to them, though, CO-TRAVELER would already have identified that all three snapped off at the same time, and figured that they all had a connection in common. Even Edward Snowden couldn't fool the NSA.

This article is from the archive of our partner The Wire.

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